Test Beam Experiment Research Articles

Virus Sensitivity Index of UV disinfection

A new concept of Virus Sensitivity Index (VSI) is defined as the ratio between the first-order inactivation rate constant of a virus, ki, and that of MS2-phage during UV disinfection, kr. MS2-phage is chosen as the reference virus because it is recommended as a virus indicator during UV reactor design and validation by the US Environmental Protection Agency. VSI has wide applications in research, design, and validation of UV disinfection systems. For example, it can be used to rank the UV disinfection sensitivity of viruses in reference to MS2-phage. There are four major steps in deriving the equation between Hi/Hr and 1/VSI. First, the first-order inactivation rate constants are determined by regression analysis between Log I and fluence required. Second, the inactivation rate constants of MS2-phage are statistically analysed at 3, 4, 5, and 6 Log I levels. Third, different VSI values are obtained from the ki of different viruses dividing by the kr of MS2-phage. Fourth, correlation between Hi/Hr and 1/VSI is analysed by using linear, quadratic, and cubic models. As expected from the theoretical analysis, a linear relationship adequately correlates Hi/Hr and 1/VSI without an intercept. VSI is used to quantitatively predict the UV fluence required for any virus at any log inactivation (Log I). Four equations were developed at 3, 4, 5, and 6 Log I. These equations have been validated using external data which are not used for the virus development. At Log I less than 3, the equation tends to under-predict the required fluence at both low Log I such as 1 and 2 Log I. At Log I greater than 3 Log I, the equation tends to over-predict the fluence required. The reasons for these may very likely be due to the shoulder at the beginning and the tailing at the end of the collimated beam test experiments. At 3 Log I, the error percentage is less than 6%. The VSI is also used to predict inactivation rate constants under two different UV disinfection scenarios such as under sunlight and different virus aggregates. The correlation analysis shows that viruses will be about 40% more sensitive to sunlight than to UV254. On the other hand, virus size of 500 nm will reduce their VSI by 10%. This is the first attempt to use VSI to predict the required fluence at any given Log I. The equation can be used to quantitatively evaluate other parameters influencing UV disinfection. These factors include environmental species, antibiotic-resistant bacteria or genes, photo and dark repair, water quality such as suspended solids, and UV transmittance.

Precision timing measurements for high energy photons

Particle colliders operating at high luminosities present challenging environments for high energy physics event reconstruction and analysis. We discuss how timing information, with a precision on the order of 10ps, can aid in the reconstruction of physics events under such conditions. We present calorimeter based timing measurements from test beam experiments in which we explore the ultimate timing precision achievable for high energy photons or electrons of 10GeV and above. Using a prototype calorimeter consisting of a 1.7×1.7×1.7cm3 lutetium–yttrium oxyortho-silicate (LYSO) crystal cube, read out by micro-channel plate photomultipliers, we demonstrate a time resolution of 33.5±2.1ps for an incoming beam energy of 32GeV. In a second measurement, using a 2.5×2.5×20cm3 LYSO crystal placed perpendicularly to the electron beam, we achieve a time resolution of 59±11ps using a beam energy of 4GeV. We also present timing measurements made using a shashlik-style calorimeter cell made of LYSO and tungsten plates, and demonstrate that the apparatus achieves a time resolution of 54±5ps for an incoming beam energy of 32GeV.

Development of a silicon micro-strip detector for tracking high intensity secondary beams

A single-sided silicon micro-strip detector (SSD) has been developed as a tracking detector for hadron experiments at J-PARC where secondary meson beams with intensities of up to 108Hz are available. The performance of the detector has been investigated and verified in a series of test beam experiments in the years 2009–2011. The hole mobility was deduced from the analysis of cluster events. The beam rate dependence was measured in terms of timing resolution, signal-to-noise ratio, and hit efficiency. This paper describes the detector with its read-out system, details of the test experiments, and discusses the performance achieved.

Event reconstruction in the RICH detector of the CBM experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment at the future FAIR facility will investigate the QCD phase diagram at high net-baryon densities and moderate temperatures. One of the key signatures will be di-leptons emitted from the hot and dense phase in heavy-ion collisions. Measuring di-electrons, a high purity of identified electrons is required in order to suppress the background. Electron identification in CBM will be performed by a Ring Imaging Cherenkov (RICH) detector and Transition Radiation Detectors (TRD). In order to access the foreseen rare probes, the detector and the data acquisition have to handle interaction rates up to 10MHz. Therefore, the development of fast and efficient event reconstruction algorithms is an important and challenging task in CBM. In this contribution event reconstruction and electron identification algorithms in the RICH detector are presented. So far they have been developed on simulated data but could already be tested on real data from a RICH prototype testbeam experiment at the CERN-PS. Efficient and fast ring recognition algorithms in the CBM-RICH are based on the Hough Transform method. Due to optical distortions of the rings, an ellipse fitting algorithm was elaborated to improve the ring radius resolution. An efficient algorithm based on the Artificial Neural Network was implemented for electron identification in RICH. All algorithms were significantly optimized to achieve maximum speed and minimum memory consumption.

Heavily irradiated N-in-p thin planar pixel sensors with and without active edges

We present the results of the characterization of silicon pixel modules employing n-in-pplanar sensors with an active thickness of 150 μm, produced at MPP/HLL, and 100–200 μm thin active edge sensor devices, produced at VTT in Finland.These thin sensors are designed as candidates for the ATLAS pixel detector upgrade to be operated at the HL-LHC, as they ensure radiation hardness at high fluences. They are interconnected to theATLAS FE-I3 and FE-I4 read-out chips.Moreover, the n-in-p technology only requires a single side processing and thereby it is a cost-effectivealternative to the n-in-n pixel technology presently employed in the LHC experiments.High precision beam test measurements of the hit efficiency have been performed on thesedevices both at the CERN SpS and at DESY, Hamburg. We studied the behavior of thesesensors at different bias voltages and different beam incident angles up to the maximum oneexpected for the new Insertable B-Layer of ATLAS and for HL-LHC detectors.Results obtained with 150 μm thin sensors, assembled with the new ATLAS FE-I4 chip andirradiated up to a fluence of 4 × 1015 neq/cm2, show that they are excellent candidates for largerradii of the silicon pixel tracker in the upgrade of the ATLAS detector at HL-LHC. In addition, the active edge technologyof the VTT devices maximizes the active area of the sensorand reduces the material budget to suit the requirements for the innermost layers.The edge pixel performance of VTT modules has been investigated at beam test experiments andthe analysis after irradiation up to a fluence of 5 × 1015 neq/cm2 has been performed using radioactive sources in the laboratory.

Performance of high-resolution position-sensitive detectors developed for storage-ring decay experiments

As next generation spectroscopic tools, heavy-ion cooler storage rings will be a unique application of highly charged RI beam experiments. Decay spectroscopy of highly charged rare isotopes provides us important information relevant to the stellar conditions, such as for the s- and r-process nucleosynthesis. In-ring decay products of highly charged RI will be momentum-analyzed and reach a position-sensitive detector set-up located outside of the storage orbit. To realize such in-ring decay experiments, we have developed and tested two types of high-resolution position-sensitive detectors: silicon strips and scintillating fibers. The beam test experiments resulted in excellent position resolutions for both detectors, which will be available for future storage-ring experiments.

A time-of-flight system for the external target facility

A time-of-flight system with a plastic scintillator coupled to photomultipliers is developed for the external target facility (ETF). This system can satisfy the requirement of an ultrahigh vacuum (∼10−9 mbar), a high counting rate (∼106 particles per second) and a magnetic field environment. In the beam test experiment, a total time resolution of 580 ps FWHM was obtained for the whole system, and nuclei with a mass of up to 80 could be identified using this system.

LePIX: First results from a novel monolithic pixel sensor

We present a monolithic pixel sensor developed in the framework of the LePIX project aimed at tracking/triggering tasks where high granularity, low power consumption, material budget, radiation hardness and production costs are a concern. The detector is built in a 90nm CMOS process on a substrate of moderate resistivity. This maintains the advantages usually offered by Monolithic Active Pixel Sensors (MAPS), like a low input capacitance, having a single piece detector and using a standard CMOS production line, but offers charge collection by drift from a depleted region and therefore an excellent signal to noise ratio and a radiation tolerance superior to conventional undepleted MAPS.Measurement results obtained with the first prototypes from laser, radioactive source and beam test experiments are described. The excellent signal-to-noise performance is demonstrated by the capability of the device to separate the peaks in the spectrum of a 55Fe source. We will also highlight the interaction between pixel cell design and architecture which points toward a very precise direction in the development of such depleted monolithic pixel devices for high energy physics.

Design and Studies of μ-strip Stacked Module Prototypes for Tracking at Super-LHC

Abstract Experience at high luminosity hadrons collider experiments shows that tracking information enhances the trigger rejection capabilities while retaining high efficiency for interesting physics events. The design of a tracking based trigger for Super LHC (S-LHC), the already envisaged high luminosity upgrade of the LHC collider, is an extremely challenging task, and requires the identification of high-momentum particle tracks as a part of the Level 1 Trigger.Simulation studies show that this can be achieved by correlating hits on two closely spaced silicon strip sensors. The progresses on the design and development of this micro-strip stacked prototype modules and the performance of few prototype detectors will be presented. The prototypes have been built with the silicon sensors and electronics used to equip the present CMS [1] Tracker.Preliminary results of a simulated tracker layout equipped with stacked modules are discussed in terms of pT resolution and triggering capabilities.The study of real prototypes in terms of signal over noise and tracking performance with cosmic rays and a dedicated beam test experiment will also be shown.

Improvements in the Geant4 Hadronic Physics

During the last five years, development of GEANT4 hadronic physics models has been driven largely by the anticipated turn-on of the LHC detectors and the subsequent comparison of new data with the simulated detector responses.Work has concentrated on three main areas: hadronic model improvement for high energy string models, intranuclear cascade models, precompound and de-excitation models, and elastic scattering which are currently used in the simulation of LHC experiments. These development are tested against a large collection of thin target data and dedicated test beam experiments using calorimeter prototypes. Salient improvements in physics and computing performance of these models will be discussed.

The National Analysis Facility at DESY - status and use cases by the participating experiments

The German National Analysis Facility (NAF) was set up at DESY, starting end of 2007 in the context of the Helmholtz Alliance "Physics at the Terascale". The NAF complements the DESY and the German Grid resources, and hence offers users from the German HEP institutes the best possible environment for data analysis. In the first part, the key aspects and components of the NAF are briefly presented with an emphasis on recent improvements. In the second part, the use cases of the three participating LHC experiments, ATLAS, CMS and LHCb, will be presented. Differences and commonalities in the usage of the NAF will be shown. Special emphasis will be placed on the usage of PROOF, whose usage on the NAF has been pioneered by CMS. It is now adapted by ATLAS. The third part will concentrate on how the NAF was used for detector optimisation studies in the preparation of one of the ILC Lol's (ILD 2009), as well as how CALICE uses the NAF for the analysis of their data taken in several test beam experiments performed for detector R & D. Finally, future developments of the NAF are presented.

Angular resolution of the gaseous micro-pixel detector Gossip

Gossip is a gaseous micro-pixel detector with a very thin drift gap intended for a high rate environment like at the pixel layers of ATLAS at the sLHC. The detector outputs not only the crossing point of a traversing MIP, but also the angle of the track, thus greatly simplifying track reconstruction. In this paper we describe a testbeam experiment to examine the angular resolution of the reconstructed track segments in Gossip. We used here the low diffusion gas mixture DME/CO 2 50/50. An angular resolution of 20 mrad for perpendicular tracks could be obtained from a 1.5 mm thin drift volume. However, for the prototype detector used at the testbeam experiment, the resolution of slanting tracks was worsened by poor time resolution of the pixel chip used.

Study of a 144 channel multi-anode hybrid avalanche photo-detector for the Belle II RICH counter

A new hybrid avalanche photo-detector has been developed as a photon sensor for the Belle II RICH counter. Single-photon response was investigated in the presence of a magnetic field and excellent performance was demonstrated. In addition, the radiation damage due to the neutron dose was studied. By building a prototype consisting of six photo-detectors, a test beam experiment was carried out. We successfully obtained a single-photon Cherenkov resolution of 13.5 mrad with 15.3 photoelectrons and achieved a π / K separation of more than 6 σ at 4 GeV/ c.

Study of transparent silica aerogel with high refractive index

Optical quality of silica aerogel with refractive index values greater than 1.06 has been remarkably improved by introducing a new fabrication technique, called “pinhole drying method”. This technique allows to produce ultra-high index aerogel up to 1.26 with excellent transparency. The transmission length of the aerogel tile with index of 1.06, obtained with the new method, was found to be doubled compared to that with conventional production. To evaluate the optical performance as a Cherenkov radiator, a prototype RICH counter was built and a test beam experiment was carried out. A clear Cherenkov ring has been observed and significant increase in the detected light yield has been confirmed.

Study of 144-channel multi-anode hybrid avalanche photo-detector for the Belle RICH counter

A new hybrid avalanche photo-detector has been developed for the Belle RICH counter. The basic features of this device were examined with and without a magnetic field. By constructing a RICH prototype counter using 6 photo-detectors, we carried out a test beam experiment to confirm the performance. We obtained a single photon Cherenkov angle resolution of 12.8mrad with 4.6 photo-electrons in our experimental setup, demonstrating that 4σπ/K separation at 4GeV/c was achieved.

Development of transparent silica aerogel over a wide range of densities

We have succeeded in developing hydrophobic silica aerogels over a wide range of densities (i.e. refractive indices). A pinhole drying method was invented to make possible producing highly transparent aerogels with entirely new region of refractive indices of 1.06–1.26. Obtained aerogels are more transparent than conventional ones, and the refractive index is well controlled in the pinhole drying process. A test beam experiment was carried out in order to evaluate the performance of the pinhole-dried aerogels as a Cherenkov radiator. A clear Cherenkov ring was successfully observed by a ring imaging Cherenkov counter. We also developed monolithic and hydrophobic aerogels with a density of 0.01g/cm3 (a low refractive index of 1.0026) as a space dust capturer for the first time. Consequently, aerogels with any refractive indices between 1.0026 and 1.26 can be produced freely.

CALICE scintillator HCAL - Electromagnetic and hadronic shower analysis

The CALICE test beam calorimeters operated at the CERN SPS facility have collected a large sample of hadronic and electromagnetic showers with unprecedented granularity.The calorimeters and beam line instrumentation are modeled in the MOKKA framework and full simulation of the test beam experiment is performed using GEANT4. Digitization is applied to each calorimeter to account for detector effects and noise. The scintillator-based hadronic calorimeter (AHCAL) is the center of the studies reported in this paper. The most important validation of the detector modeling and calibration chain is the test of the calorimeter response linearity and resolution for a large range on incident beam energies. Electromagnetic showers are the most demanding test since the energy deposited per single tile in an electromagnetic shower is larger than in a hadronic shower for the same beam energy. Results of the calorimeter response to muons and positrons are discussed and compared to Monte Carlo (MC).The analysis of single pion showers, recorded with the AHCAL offer the unique possibility to test hadronic shower models using a number of different observables. Total energy and longitudinal profiles have been studied at first and compared with two available shower models in GEANT4. Results of the effect of the shower leakage on the reconstructed energy and energy resolution are presented. Furthermore, studies of shower separation are performed using event mixing techniques. Shower separation is critical for the performance of modern particle flow algorithms, which here for the first time can be tested on experimental data.

Acoustic signals from proton beam interaction in water—Comparing experimental data and Monte Carlo simulation

The main purpose of this work is related to the opportunity of exploiting the thermo-acoustic effect of pressure pulse generation to detect high-energy neutrinos in underwater environment, in the framework of neutrino astronomy, that is a promising field of investigation in the multi-messenger approach of astrophysical research. The performances of the acoustic detection are discussed presenting an account from test measurements carried out with proton beams at the ITEP accelerator facilities. Combining results from data analysis and Monte Carlo simulation, the potentials of the simulation itself are explored, through comparisons between acquired and simulated pulse and with results from past experiments at proton beams. In addition, the Monte Carlo simulation can provide some indication on parameters that stayed undetermined during the data taking. The presented material is a conclusive report on the ITEP test beam experiment and it represents a good starting point for future developments, both in calibrations (acquired experience and software achievements can be used to plan coming experiments at test beams) and in the study of the neutrino case (computation of neutrino-induced acoustic pulses in water).

Design of a cooling system for the ITER Ion Source and Neutral Beam test facilities

This paper deals with the requirements, operational modes and design of the cooling system for the ITER Neutral Beam test experiments. Different operating conditions of the experiments have been considered in order to identify the maximum heat loads that constitute, with the inlet temperature and pressure at each component, the design requirements for the cooling system. The test facility components will be actively cooled by ultrapure water realizing a closed cooling loop for each group of components. Electrochemical corrosion issues have been taken into account for the design of the primary cooling loops and of the chemical and volume control system that will produce water with controlled resistivity and pH. Draining and drying systems have been designed to evacuate water from the components and primary loops in case of leakage, and to carry out leak detection. Tritium concentration, water resistivity and pH will be measured and monitored at each primary loop for safety reasons and high voltage holding reliability. The measured water flow rates and temperatures will be used to calculate the exchanged heat fluxes and powers. Flow regulating valves and speed of variable driven pumps will be adjusted to control the component temperatures in order to fulfil the functional and thermohydraulic requirements.

Study of a silica aerogel for a Cherenkov radiator

Highly transparent silica aerogel has been developed for a Cherenkov radiator in a RICH detector to be installed into the Belle forward end-cap apparatus. We have improved the aerogel optical properties for a wide range of refractive indices around 1.03–1.07. The parameters that control a synthesis process in the aerogel production were successfully optimized, and the obtained transmission length for this index range was almost doubled. A prototype was constructed using newly produced aerogel samples in order to carry out a test beam experiment, and a remarkable increase in the Cherenkov light yield was confirmed. The uniformity of refractive index in an aerogel block was examined using an X-ray tomography device and the deviation was found to be sufficiently small. Furthermore, the production of a monolithic aerogel consisting of two layers with different refractive indices is also described.